cleanup errors and fix a couple field negative tests

frog/world.dart

Index: frog/world.dart
diff --git a/frog/world.dart b/frog/world.dart
index 8a7e58b173a70cfea592a66d27c52fb076910958..92e90250e6bb4346dc5d3b6138ffd1e8fad85f54 100644
--- a/frog/world.dart
+++ b/frog/world.dart
@@ -360,7 +360,7 @@ class World {
   // ********************** Message support ***********************
 
   void _message(String message, SourceSpan span, SourceSpan span1,
-      bool throwing) {
+      SourceSpan span2, bool throwing) {
     var text = message;
     if (span != null) {
       text = span.toMessageString(message);
@@ -369,6 +369,9 @@ class World {
     if (span1 != null) {
       print(span1.toMessageString(message));
     }
+    if (span2 != null) {
+      print(span2.toMessageString(message));
+    }
 
     if (throwing) {
       throw new CompilerException(message, span);
@@ -376,39 +379,39 @@ class World {
   }
 
   /** [message] is considered a static compile-time error by the Dart lang. */
-  void error(String message, [SourceSpan span, SourceSpan span1]) {
+  void error(String message, [SourceSpan span, SourceSpan span1, SourceSpan span2]) {
     errors++;
-    _message('error: $message', span, span1, options.throwOnErrors);
+    _message('error: $message', span, span1, span2, options.throwOnErrors);
   }
 
   /** [message] is considered a type warning by the Dart lang. */
-  void warning(String message, [SourceSpan span, SourceSpan span1]) {
+  void warning(String message, [SourceSpan span, SourceSpan span1, SourceSpan span2]) {
     warnings++;
     if (options.showWarnings) {
-      _message('warning: $message', span, span1, options.throwOnWarnings);
+      _message('warning: $message', span, span1, span2, options.throwOnWarnings);
     }
   }
 
   /** [message] at [location] is so bad we can't generate runnable code. */
-  void fatal(String message, [SourceSpan span, SourceSpan span1]) {
+  void fatal(String message, [SourceSpan span, SourceSpan span1, SourceSpan span2]) {
     errors++;
     seenFatal = true;
-    _message('fatal: $message', span, span1,
+    _message('fatal: $message', span, span1, span2,
      options.throwOnFatal || options.throwOnErrors);
   }
 
   /** [message] at [location] is about a bug in the compiler. */
-  void internalError(String message, [SourceSpan span, SourceSpan span1]) {
-    _message('We are sorry, but... $message', span, span1, true);
+  void internalError(String message, [SourceSpan span, SourceSpan span1, SourceSpan span2]) {
+    _message('We are sorry, but... $message', span, span1, span2, true);
   }
 
   /**
    * [message] at [location] will tell the user about what the compiler
    * is doing.
    */
-  void info(String message, [SourceSpan span, SourceSpan span1]) {
+  void info(String message, [SourceSpan span, SourceSpan span1, SourceSpan span2]) {
     if (options.showInfo) {
-      _message('info: $message', span, span1, false);
+      _message('info: $message', span, span1, span2, false);
     }
   }